Mathematics
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OpenStudy (studygurl14):
What do I do now? calculus problem @mathmale
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OpenStudy (studygurl14):
OpenStudy (studygurl14):
@mathmale @hero @Zarkon
OpenStudy (zarkon):
\[e^{-x}\] is a decreasing function...just look at the endpoints
OpenStudy (studygurl14):
I have to do it without graphing.
OpenStudy (studygurl14):
@tkhunny @Hero
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OpenStudy (zarkon):
you don't need to graph it
OpenStudy (zarkon):
\[f(x)=e^{-x}\]
\[f'(x)=-e^{-x}<0\] and therefore it is decreasing
OpenStudy (zarkon):
since it is decreasing the max will be at \(x=-1\) and the min will be at \(x=1\)
OpenStudy (studygurl14):
Okay, thank you
OpenStudy (studygurl14):
What about the critical point part of the question?
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OpenStudy (studygurl14):
@xapproachesinfinity
OpenStudy (xapproachesinfinity):
e^-x is strictly decreasing so there is no critical points
OpenStudy (xapproachesinfinity):
remember crtical point occur when the g' changes sign
but here -e^-x <0 all the time no sign change
OpenStudy (xapproachesinfinity):
i mean extrema no critical points in general
OpenStudy (studygurl14):
I thought a criticall point was where g'(x) = 0
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OpenStudy (xapproachesinfinity):
no g' is never zero, and yes critical points are found with g'=0
or g' does not exist
OpenStudy (xapproachesinfinity):
here g' is defined for all x
and g' does not equal zero
hence no critical points
OpenStudy (xapproachesinfinity):
oh one second i didn't see -1<=x<=1
OpenStudy (xapproachesinfinity):
there is max and min in this case
OpenStudy (xapproachesinfinity):
g(-1) and g(1) are max and min respectively
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OpenStudy (xapproachesinfinity):
but still we say critical point don't exist
OpenStudy (studygurl14):
Okay, so what would I say to answer the second part of the question?
OpenStudy (xapproachesinfinity):
if we are just talking about extrema
absolute max and min exist
OpenStudy (xapproachesinfinity):
the question asked you for extrema first
critical points don't exist for second part
OpenStudy (xapproachesinfinity):
stationary point are critical points where g'=0
i just learned that know lol :)
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OpenStudy (xapproachesinfinity):
i mean i never heard stationary before
OpenStudy (studygurl14):
Ok, thank you
OpenStudy (xapproachesinfinity):
welcome :)